Husqvarna K770 SmartGuard Instruction manual

Workshop manual
K770 SmartGuard
English
1453 - 001 - 02.04.2020

Contents
1 Introduction
1.1 Document description............................................ 3
1.2 Target group...........................................................3
1.3 Revisions................................................................3
1.4 Safety..................................................................... 3
1.5 Servicing tools........................................................3
2 Safety
2.1 Safety definitions....................................................4
2.2 General safety instructions.....................................4
2.3 Symbols on the product......................................... 4
3 Servicing data
3.1 Symbols in the diagrams........................................5
3.2 Tightening torques................................................. 6
4 Servicing tools
4.1 Servicing tools overview.......................................10
4.2 Servicing tools overview.......................................11
4.3 Servicing tools overview.......................................12
5 Product overview for repair and servicing
5.1 Components.........................................................13
5.2 Basic modules of the product...............................14
6 Repair and servicing
6.1 Starter.................................................................. 22
6.2 Ignition system..................................................... 25
6.3 Flywheel............................................................... 29
6.4 Air filter................................................................. 30
6.5 Fuel system..........................................................31
6.6 Carburetor............................................................ 33
6.7 Decompression valve...........................................42
6.8 Cylinder and piston.............................................. 43
6.9 Piston wear.......................................................... 46
6.10 To assemble the piston...................................... 47
6.11 To assemble the cylinder................................... 48
6.12 Crankcase.......................................................... 48
6.13 Clutch................................................................. 54
6.14 Cutting head.......................................................57
6.15 Wet system........................................................ 65
6.16 Throttle trigger and throttle trigger lockout......... 67
6.17 OilGuard.............................................................68
7 Troubleshooting
7.1 Engine does not start........................................... 70
7.2 Engine stops during operation - no sparks...........71
7.3 Engine stops during operation............................. 71
7.4 Weak output or change of speed......................... 72
7.5 Other engine problems.........................................72
8 Wiring diagram
8.1 Wiring diagram OilGuard......................................73
21453 - 001 - 02.04.2020

1 Introduction
1.1 Document description
This manual gives a full description of how to do
maintenance and repair on the product. It also gives
safety instructions that the personnel must obey.
1.2 Target group
This manual is for personnel with a general knowledge
of how to do repair and do servicing. All personnel that
do repair or do servicing on the product must read and
understand the manual.
1.3 Revisions
Changes to the product can cause changes to the
maintenance work and spare parts. Separate
information is sent out for each change.
Read the manual together with all received information
about changes to maintenance and spare parts for the
product.
1.4 Safety
WARNING: All personnel that repair or do
servicing on the product must read and
understand the safety instructions in this
workshop manual.
1.5 Servicing tools
The manual gives information about necessary servicing
tools. Always use original tools from Husqvarna.
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2 Safety
2.1 Safety definitions
The definitions below give the level of severity for each
signal word.
WARNING: Injury to persons.
CAUTION: Damage to the product.
Note: This information makes the product easier to use.
2.2 General safety instructions
• Do not repair the product unless you have read and
understood this workshop manual.
• The service center where the product is repaired
must have safety equipment approved by local
bylaws.
• The product is examined and approved only with the
equipment given or recommended by the
manufacturer.
• Prevent health and safety risks. All personnel must
obey laws and requirements when they do the
procedures given in this manual.
• Obey the local waste regulations.
• Always make sure that all nuts and bolts are
correctly tightened.
• Use protective gloves and eye protection. Goggles
must obey the ANSI Z87.1 for US or EN166 for EU
countries.
• When using compressed air, do not point it to your
body. Air can go into the bloodstream.
• Use hearing protection when the engine is started.
• The product can make sparks and cause ignition of
flammable materials.
• Replace all damaged or missing warning symbol
decals.
• Gasoline and its fumes are poisonous.
• Gasoline can cause damage to the eyes and the
skin.
• Gasoline can cause breathing problems.
• Gasoline is flammable.
2.3 Symbols on the product
WARNING: This product can be
dangerous and cause serious injury or
death to the operator or others. Be careful
and use the product correctly.
Read the operator's manual carefully and
make sure that you understand the
instructions before you use this product.
Use approved protective helmet, hearing
protection, eye protection and respiratory
protection.
This product complies with applicable EC
Directives.
Dust forms when cutting. The dust can
cause injuries if inhaled. Use an approved
respiratory protection. Avoid inhaling
exhaust fumes. Always provide for good
ventilation.
WARNING! Kickbacks can be sudden,
rapid and violent and can cause life
threatening injuries.
Sparks from the cutting blade can cause
fire in fuel, wood, clothes, dry grass or
other flammable materials.
Make sure that the cutting blade does not
have cracks or other damages.
Do not use circular saw blades.
Choke
Air purge bulb
Decompression valve
Starter rope handle
Use a fuel mixture of gasoline and oil.
Note: Other symbols/decals on the product refer to
special certification requirements for some markets.
4 - Safety 1453 - 001 - 02.04.2020

3 Servicing data
3.1 Symbols in the diagrams
Tightening torque, Nm
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3.2 Tightening torques
3-5
4-6
4-6
4-6
2,0
7-9
3-5
4-6
6 - Servicing data 1453 - 001 - 02.04.2020

11-12
10-12
5-7
11-13
11-13
11-13
7-9
17-23
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25-30
1-1.5
9-11
1-1.5
38-42
14-16
4-10
6-8
6-8
14-16
0.5-0.8
4-6
5-7
8-10
8 - Servicing data 1453 - 001 - 02.04.2020

13
6-8
20-25
5
5-6
10-12
6
6
4
3
5-7
5
6-8 25-30
9-11
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4 Servicing tools
4.1 Servicing tools overview
0,3 mm
1 2 3
4 5 6
7 8 9
Po-
si-
tion
Designation Used for Order No./
Source
1 Air clearance gauge To adjust the air clearance between the ignition module and the fly-
wheel.
502 51 34-02
2 Assembly punch To assemble the sealing rings of the crankshaft in the crankcase. 502 50 82-01
3 Bearing press To disassemble the primary bearing and assemble the crankshaft. 544 10 36-02
4 Bearing press To assemble the primary bearing and assemble and disassemble
blade shaft bearing and axle.
506 37 61-02
5 Bearing puller Remove the primary bearing from the crankshaft. 531 00 48-67
6 Combination wrench General. 506 38 26-01
7 Compression tester To examine the compression in the cylinder. 531 03 16-86
8 Bearing press To disassemble and assemble the clutch drum ball bearing. 504 56 79-01
9 Cylinder seal To examine the crankcase for leaks. 544 10 33-01
10 - Servicing tools 1453 - 001 - 02.04.2020

4.2 Servicing tools overview
10 11 12
13 14 15
16 17 18
Po-
si-
tion
Designation Used for Order No./Source
10 Flywheel puller To disassemble the flywheel. 502 51 49-02
11 Grip plate To divide the crankcase. 544 06 00-02
12 Gudgeon pin punch To disassemble and assemble the gudgeon pin. 505 38 17-05
13 Hose catcher To catch the fuel filter in the tank. 502 50 83-01
14 Kit for piston service To do service on the piston. 502 50 70-01
15 Piston stop To disassemble the clutch. 504 91 06-05
16 Pressing device To disassemble and assemble the blade shaft bearings and axle. 575 96 20-01
17 Pressure tester To examine the carburetor, fuel lines and check valve. 501 56 27-01
18 Pressure tester To examine the crankcase for leaks. 531 03 06-23
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4.3 Servicing tools overview
19 20 21
22 23 24
25 26
Po-
si-
tion
Designation Used for Order No./
Source
19 Puller To disassemble the sealing rings of the crankcase in the crankcase. 504 91 40-01
20 Sealing plug To examine the crankcase for leaks. 503 55 22-01
21 Special screwdriver To adjust the idle speed. 501 60 02-03
22 Tachometer To adjust the idle and maximum speed. 502 71 14-01
23 Test spark plug To do servicing on the ignition unit. 502 71 13-01
24 Universal puller To disassemble the support washer of the clutch on the crankshaft.
To divide the crankcase.
504 90 90-02
25 Key Torx T27 General use. 502 71 27-02
26 Grease To apply on the bushings of the 588 81 48-01
12 - Servicing tools 1453 - 001 - 02.04.2020

5 Product overview for repair and servicing
5.1 Components
10
1
2
3
4
9
8
7
5
24
23
27
25
26
12
15
11
14
13
16
17
18
19
20
21
6
22
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servicing - 13

1.
2. Adjustment handle for blade guard
3. Water hose
4. Water valve
5. Air filter cover
6. Rear handle
7. Starter rope handle
8. Starter
9. Ground support
10. Cutting blade
11. Guide wheels
12. Handle
13. Front handle
14. Combination wrench
15. Cover for springs
16. Lock screws for belt adjustment
17. Decompression valve
18. Belt adjustment screw
19. Air purge bulb
20. Fuel tank cap
21. Water connection with filter
22. Sight glass for fuel
23. OilGuard button
24. Choke lever
25. Throttle trigger lockout
26. Throttle control
27. Stop switch
5.2 Basic modules of the product
This chapter shows how you can disassemble and
assemble the product in its basic modules.
14 - Product overview for repair
and servicing
1453 - 001 - 02.04.2020

5.2.1 To remove the starter
1. Loosen the 4 screws on the guard.
2. Remove the starter.
5.2.2 To remove the cutting head
1. Loosen the hose clip. Refer to To disassemble the
wet system on page 66 . Loosen the 3 nuts on the
front belt guard.
2. Loosen the belt tension with the adjuster screw.
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servicing - 15

3. Remove the front belt guard.
4. Remove the cutting head.
5. Remove the 2 screws on the rear belt guard.
Remove the rear belt guard.
16 - Product overview for repair
and servicing
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5.2.3 To remove the air filter
1. Remove the 3 screws and remove the air filter
cover.
2. Remove the 2 screws and remove the air filter
holder and the air filter.
3. Remove the air filter.
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servicing - 17

5.2.4 To remove the cylinder cover
1. Remove the 4 screws.
2. Push the collar of the rubber seal through the hole.
3. Remove the cylinder cover.
18 - Product overview for repair
and servicing
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5.2.5 To remove the carburetor
1. Remove the screw.
2. Lift the carburetor until you can get access to the
fuel hose and the hose to the air purge bulb.
3. Remove the fuel hose from the carburetor.
4. Remove the hose to the air purge bulb.
5. Remove the throttle rod from the throttle control.
1453 - 001 - 02.04.2020 Product overview for repair and
servicing - 19

5.2.6 To remove the air duct
Remove the starter, air filter cover and cylinder cover
before you remove the air duct.
1. Lift the cable for the stop switch out of its holders.
2. Remove the ignition cable at the spark plug and lift
the cable out of its holder in the cover.
3. Remove the 3 screws on the air duct cover. Remove
the air duct cover.
5.2.7 To remove the muffler
Remove the cutting head the and the starter before you
remove the muffler.
1. Loosen the 4 screws.
2. Remove the muffler.
5.2.8 To remove the vibration damping units
1. Remove the air filter and cylinder cover. Refer to To
remove the air filter on page 17 .
2. Remove the air duct cover. Refer to To remove the
air duct on page 20
3. Remove the screw that holds the carburetor. Refer
to To remove the carburetor on page 19
4. Remove the cable lug by the ignition module. Refer
to To examine the short circuit cable and the stop
switch on page 27
5. Remove the cable at the ground point. Refer to To
remove the stop switch on page 28
20 - Product overview for repair
and servicing
1453 - 001 - 02.04.2020